International Journal of Mechanical and Production Engineering Research and Development (IJMPERD) ISSN(P): 2249-6890; ISSN(E): 2249-8001 Vol. 4, Issue 1, Feb 2014, 39-46 © TJPRC Pvt. Ltd. OPTIMISATION OF WELDING PROCESS OF COMPOSITE CHROMIUM-CARBIDE BASED TUBULAR ELECTRODE FOR HARDFACING B. BALAJI 1 , C. YUVARAJ 2 & M. L. S. DEVAKUMAR 3 1 Research Scholar, JNTUCEA, Anantapuram, Andhra Pradesh, India 2 Deparment of Mechanical Engg, Madanapalle Institute of Technology & Science, Madanapalle, Andhra Pradesh, India 3 Deparment of Mechanical Engg, JNTUCEA, Anantapuram, Andhra Pradesh, India ABSTRACT The objective of this research work was to investigate the effect of tubular electrode parameters such as baking temperature of electrode (300, 350 and 400C), duration of baking of electrode (2, 2.5 and 3 hr) and wt. % of chromium (20, 25 and 30 wt. %) on hardfaced surface. The hardfaced surface is obtained using welding process. Specimens so prepared are tested for hardness, with Rockwell hardness tester. Taguchi method is applied for predicting the optimum process parameters which maximize the hardness of hardfaced surface using composite tubular electrode. The result showed that the optimum level of process parameters to obtain good mechanical properties for the hard faced surface are 30% volume fraction of chromium, 300°C of baking and 2.5 hr of baking electrode for maximum hardness. From the analysis it was evident that the volume fraction of chromium is a major contributing factor (52.6%) for improving hardness. KEYWORDS: Tubular Electrode, Welding, Hardness, Taguchi, Hardfacing INTRODUCTION The most engineering components at some stage suffer from the varying effects of wear; it is one of the main causes of expensive material losses and cost-intensive break downs of machines and equipment. Although the process of wear is unavoidable, it can be reduced. The methods employed for the reduction of wear fall into two categories: surface treatments and coating processes [1]. Hard facing is a low-cost method of depositing wear-resistant surfaces on metal components which are exposed to high abrasion environment to extend their service life [2]. For hard facing composite tubular electrode is used, which is a basically coated, alloyed electrode which deposits complex chromium carbides in an iron rich ferrite matrix. It is resistant to both abrasion (coarse and fine) and impact loading (moderate to heavy) [3]. Tubular electrodes are filled with metal powders (carbides of Cr and Nb) with base alloy powders. This electrode produces a deposit characterised by an exceptional hardness and resistance to abrasion, combined with moderate impact, higher resistance than conventional electrodes (because of the low dilution with the base metal). Hard facing is used to enhance surface properties of a metallic component, as a specially designed alloy is surface welded to achieve specific wear resistant properties. Surface properties and quality depend upon the selected alloy and welding process. Several welding techniques such as MMAW, OAW, GMAW and SAW can be used for hardfacing. The most important differences among these techniques lie in the welding efficiency, the weld plate dilution and the manufacturing cost of welding consumables. Welding parameters have been found to affect the properties of hardfacing deposits [4, 5]. The weld deposition of hardfacing alloys is commonly employed in industry to increase the service life of components subjected to abrasive wear [6-8]. Slurry erosion is a type of abrasion wear commonly encountered in slurry pump casings and impellers, which decreases their life and requires frequent replacement. To increase in-service operation